1. Field of Invention
The present invention relates to an energy storage device packaging method and, in particular, to a packaging method for electric power storage units of an ultracapacitor energy storage device.
2. Related Art
A battery is a power device that converts energy of a certain form directly into electrical power without going through an intermediate mechanical conversion process. A capacitor is an electronic device that stores charges. In general, batteries can store a large amount of energy but have a lower output power, while capacitors store little energy but can have a high output power. Therefore, batteries are considered as an electrical power storage device and capacitors are power storage devices. They are used by human beings in various applications.
With the arrival of the 3C (computer, communications, and consuming electronics) era, light, thin, short and small electronic products with multiple functions and high efficiency are more and more popular in our daily lives. Such products include notebook computers, mobile phones, walkmans, etc. To make electronic products portable and good for long term uses, a sufficient portable power supply becomes the key problem. Conventional combinations of batteries and capacitors obviously cannot satisfy modem uses. A new energy storage device, the ultracapacitor, has thus been invented.
Conventional capacitors use an insulating material or a dielectric sandwiched between two conductors to achieve the isolation effect. The capacitance is produced by separating opposite charges on the conductor surfaces.
The electrochemical double layer (EDL) adopted in ultracapacitor energy storage devices does not have an insulating material to establish a dielectric layer. The charging and energy storage occurs at the interface of the EDL. The ultracapacitor can achieve an energy density and a power density far higher than the conventional capacitor technology can. In comparison with conventional batteries, ultracapacitors can release more than 100 times of power and store over 20 times of electrical energy.
Currently, ultracapacitor energy storage devices have gone from the experimental phase into a few commercialized applications. The product applications also gradually move from defensive satellites and military uses to products in vehicle, mechanical-electrical and communication electronics industries.
Please refer to FIGS. 1A and 1B for the structure and the fabrication method of a conventional ultracapacitor energy storage device. The method proposed in the U.S. Pat. No. 5,384,685, 5,464,453, 5,711,988, 5,800,857, and 5,821,033 is to dispose two gaskets 12 between two electrodes 11. A block 13 is sandwiched between the two gaskets 12, forming a stack structure 10. The gasket is formed by using a polymer gel to form a film and then cutting off the shape needed. The large surface covering layer 16 of the inner surface of the electrode 11 can be formed with a proper little bump 17 to help supporting and insulating the two electrodes 11.
Afterwards, the two gaskets 12 are heated for reflowing so as to bind the two electrodes 11 and the two gaskets 12 together, forming an enclosed gap 15 in the stack structure 10.
After cooling to the room temperature, the block 13 is withdrawn to form a refill port 14 on a side surface of the stack structure 10. An electrolyte solution is filled into the gap 15 inside the stack structure 10 through the refill port 14. Finally, the refill port 14 is closed to complete the packaging of an electric power storage unit.
However, the above packaging method has to form a gasket by making a film from polymer gel and cutting the shape needed in order to make the stack structure and refill port of the electric power storage unit before putting in the electrolyte solution and enclosing the refill port. The process is too complicated and not suitable for mass production. Therefore, it is desirable to have a new packaging method that solves the above problems.
In view of the foregoing, the invention provides a packaging method for electric power storage units of an ultracapacitor energy storage device that has a simplified procedure and is suitable for mass production.
The disclosed packaging method directly fills in an electrolyte solution during the electrode stacking process, omitting the steps of scraping electrode sides, making polymer gel films, cutting the shape needed, and forming and enclosing a refill port. Therefore, it largely simplifies the process, increases the production efficiency and lowers the cost.
The packaging method includes the following steps:
Coating a glue wall: coating an annular glue wall along the upper surface border of a first electrode;
Filling in an electrolyte solution: filling an electrolyte solution in the upper surface of the first electrode enclosed by the annular glue wall;
Stacking electrodes: stacking a second electrode on the first electrode;
Reflowing the glue wall: heating to reflow the annular glue wall to bind the first electrode, the second electrode, and the annular glue wall together, enclosing the electrolyte solution between the first electrode and the second electrode.
The annular glue wall is composed of materials that are acid-resistant and adhesive to the electrode. For example, the material can be a thermal plastic resin that can be heated for reflowing and congregation.
The lower surface of the second electrode can be formed with a second annular glue wall, corresponding to the first annular glue on the upper surface of the first electrode. The first annular glue wall and the second annular glue wall can be heated and reflowed to enclose the electrolyte solution so that the electric power storage unit has a good closure.
In the step of coating a glue wall, hot air, infrared, ultraviolet or radiation heating can speed up the congregation of the annular glue walls. The heat source in the step of reflowing the glue wall can be ultrasonic waves, hot air or infrared light.
A separation plate can be installed on the upper surface of the first electrode as the support structure of the electric power storage unit, preventing a direct contact between the two electrodes due to bending. The separation plate has to have the properties of being porous, acid-resistant, and thin, such as a glass fiber plate.